Electrical testing instrument



H. FAHLENBERG.

ELECTRICAL TESTING INSTRUMENT.

APPLICATION FILED OCT. 2, 1919.

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HERMANN FAHLENBERG, OF PNKOW, NEAR BERLIN, GERMANY, ASSTGNOR T0 RICHARD A'. HANSEMANN, OF BERLIN, GERMANY.

ELECTRTCAL TESTING INSTRUMENT.

Application filed October 2, 1919. Serial No. 327,925.

To all whom t may concern:

Be. it known that I, HERMANN FAHLEN- BERG, a citizen of Germany, residing at and Whose post-office address is Pankow, near Berlin, Pestalozzistrasse 29, Germany, have invented certain new and useful lmprovements in Electrical Testing Instruments, of which the following is a specification..

This invention relatesv to instruments by which electrical circuits, apparatus, etc., may be tested in order to ascertain if they are in good working order. To this end the instrument `is furnished with a lamp, a buzzer and a switch the arrangement ot which is such as to enable the lamp to be switched on and o'll at will torillumination purposes and to permit ofthe conducting parts of electrical installations being tested for the purpose of ascertaining whether they are in good working order, or whether they are connected to a source of current.

A manner ot' carrying out the invention is illustrated in the drawing in which- Fig. 1 shows the circuits and Fig. 2 an external view ot the instrument.

As shown in Fig. 2 the external appearance ot the instrument resembles that oth an electrical pocket lamp, or that of a small tiat casing which may be hung up by means'ot'. a suspender T. Enclosed in the casing is a battery B. 'llhe instrument also comprises a lamp L and a. buzzer S. Two test pegs l" and P2 are connected by conducting cords to the casing. In the interior of the casing two cylindrical switches `\V1 .and wW2 are placed which may be turned from without by means of milled handles G1 and G2. The switch lV' consists oi' two groups of adjacent segments 1, 2, 3, 4 partly conducting and partly non-conducting. The switch 2 is also composed of a group of segments l', 2', 3', el of this kind. rl`he switches are shown in Fig. l as they would appear it their pei'iplieries were spread out fiat.

When the switches 71 and "2 are in the positions illustrated in Fig. l the contact springs a., I), c, (I, and e connected to various wires lie upon insulating portions ot' the switch W1. But the contact springs f and f/ engage with the conducting segment l ot' the switch W2. lt is apparent that. when the switches are in this position, current will tlow from the positive pole ol the battery B through the wire l to thel contact spring f and through the conducting segn'ient 1 to the contact y, and thence through the wire zito the lamp L and the wire le to the negative pole of the battery. The other circuits are lall broken at theinsulating segments l of the switch` TV1. Thus with this circuit combination the instrument serves as an ordinary pocket lamp and may be used for facilitating the inspection of obscurel dcvices-and wires.

If the instrument is to be used t'or testiiur whether a conductor of an electrical in stallation has a break in it, the switch lV] is turned into its position 2. which results-in the contact springs I) and c being interconnected by a conducting segment. Then the testing pegs P1 and P2 are brought into contact with the points of the conducting part to be tested. lf this part or wire allows the current to pass in the proper manner a circuit will be established which may be traced from the positive pole of the batterv through the wire la., thespring c, the segnient 2 of the switch W, spring o. wire 7, peg l", the conductor under test. peg P2, wire 1n, buzzer S and wire nback to the bat-v tery. 'The buzzer S will thus be actuated. indicating that the circuit just' described is closed, and hence that the conductor being tested is in oi'der. lt' the buzzer tails to sound. this will indicate that there is a break somewhere in the tested conductor.

lt the instrument is to be used for testing the condition of some electrical device such as a bell, a lamp or the like. the switch ll is turned into position Z5 in which not only the contact springs o, c but also the two contact springs d, e are interconnected. On t'hc two terminals of the device to be tested now being touched by the t-wo test pegs l, ,lk the following circuit will be established: positive pole ot the battery, wire lz., spring c, spring o, wire l, test pegl l. lamp or bell. etc., being tested, test peg l". wire o. spring c. spring wire p, wire negative pole ot' the battery. ln making this test the buzzer is short-circuited.

Finally the instrument may be used to ascertain whether an existing source ot current is still active or it' a wire supposed to be carrying current is really alive". To this end the switch ll is turned into position 4 and the two test pegs l` l2 are tapped against the poles ot` the battery .or source ot' current to be tested, or against different points ot' the said wire. circuit llO is then established which may be traced from the source of current through the test peg P1, wire Z, contact spring b, contact spring a, wire g, wire 7c, wire n., buzzer S, wire m, test peg P2 and back to the source of current belng tested. The buzzer S will be actuated if the source of current or current-carr ing wire is really active".l When the switc Wl is in its position 4 the springs d and e rest upon an insulating segment which opens the circuit of the battery B of the instrument,

In the instrument illustrated, the switch W2 is provided with four segments in order to simplify the manner of using the instrument by giving it the same number ot posi-A tions as the switch W1. In the positions .l and 3 the lamp is switched on, and in the positions 2 and 4 it is off. The two switches are manipulated independently of each other.

I claimz' An instrument for testing electrical circuits comprising a portable casing including a battery, a buzzer, u lamp, test pegs, a primary combination of conductors for cstablishing a circuit including the buzzer, the battery und an external conductor to be tested, a secondary combination of conductors for establishing a circuit including the battery and un external electrical device to be tested, u tertiary combination of conductors for establishing a circuit including an external source of current and the buzzer,

und a, switch for effecting the said combinations.

In witness whereof vI have amxcd my signature in presence of two witnesses.

HERMANN FAHLENBEMI. Witnesses E. HoLsrrnnMAN7 CHARLES DURRILL. 

